1. Field of the Invention
The present invention relates to a light-emitting diode lamp (hereinafter referred to as “LED lamp”) in which a single light-emitting element or a plurality of light-emitting elements, and leads and wires electrically connected to the single or plurality of light-emitting element(s) are packed in a package such as a synthetic resin package and sealed with a light-transmissive material such as a transparent epoxy resin. Incidentally, in this specification, an LED chip itself is called “light-emitting element” whereas a light-emitting device having a plurality of LED chips mounted therein is collectively called “light-emitting diode lamp” or “LED lamp”, further, more comprehensively called “LED device”. A lead frame as a raw material thereof is called “LED lead frame”.
2. Description of the Related Art
A surface mounting chip LED (SMD) type LED lamp has been heretofore used in a light source for a backlight unit, or the like. In the SMD type LED lamp, a plurality of metal leads disposed in an injection-molded synthetic resin package, and a plurality of light emitting elements mounted on one of the leads and electrically connected to the other leads by wire-bonding are entirely sealed with a transparent epoxy resin or the like.
In the LED lamp having such a plurality of light-emitting elements, however, luminous intensity distribution characteristic varies in accordance with the respective light-emitting elements. Moreover, heat-radiating characteristic is worsened compared with that of a package of a single light-emitting element. Hence, the respective light-emitting elements become uneven both in heat-radiating characteristic and in light-emitting efficiency. In addition, there arises a problem that color-mixing characteristic is worsened when a plurality of light-emitting elements different in wavelength are mounted in the LED lamp.
Further, in this LED lamp, however, lead portions (LED loads) by which the lamp is bonded on the mount board via solder is made flat. The viscosity of solder is reduced instantaneously when the LED lamp is made to pass through a reflow furnace at a high temperature in order to solder the LED lamp onto the mount board. For this reason, surface tension of solder is applied on the lead portions but the LED lamp is hardly positioned because the lead portions are so flat that the LED lamp slides. For this reason, in the LED lamp having such leads bent once, there is a problem that accurate mounting can be hardly made.
Still further, an example of a related-art LED lead frame for the LED lamp will be described with reference to FIG. 7. FIG. 7 is a plan view showing the configuration of the related art LED lead frame.
As shown in FIG. 7, in the LED lead frame 21, four electrically conductive leads 25a, 25b, 25c and 25d are protruded inward from an outer frame 23 so that an injection-molded synthetic resin package 22 is fixed to tips of the leads. A plurality of light-emitting elements are mounted in the package 22, electrically connected to the LED lead frame 21 by wire-bonding and then sealed with a scaling resin. Thus, a body portion of an LED lamp is produced. Then, the electrically conductive leads 25a, 25b, 25c and 25d are cut into a predetermined length and then bent along the outer circumference of the package 22. Thus, a surface-mountable LED lamp is obtained.
In the LED lead frame 21, however, nothing supports the package 22 after the electrically conductive leads 25a, . . . , and 25d are cut. Therefore, the package 22 must be fixed by a jig or something when the electrically conductive leads 25a, . . . , and 25d are to be bent back or forth along the outer circumference of the package 22. For this reason, there is fear that the package 22 may be broken. Moreover, the electrically conductive leads 25a, . . . , and 25d cannot be bent accurately because the package 22 cannot be fixed firmly. Hence, there is a problem that, inconsistency in positioning accuracy with respect to a partner member may occur in a post-process.